When adding a marker in WP Go Maps, as soon as you start typing, we start looking for the best possible match for your query, based on your location. This is called the AutoComplete functionality.
If you are a free user of our plugin and have not yet created your own Google Maps API key, you are limited to 10 autocomplete searches a day.
In order to overcome this you will need to create your own API key and enjoy (nearly) unlimited AutoComplete searches.
In order for you to enjoy WP Go Maps as a first time user, and to provide you with a fuller user experience, we provide you with a temporary Google API key (which is used to display your map as well as geocode marker addresses). As you can imagine, having 400 000 domains using our API key and autocomplete functionality, we incur serious costs with Google ourselves. We've been forced to have to limit free users in order to not allow our API key to be abused and overused and to limit our own internal costs. Again, creating your own API key (which is free for 99% of users), will overcome this hurdle and you can continue to add as many markers as you like.